Apparatus and method for beam management in wireless communication system

ABSTRACT

A pre-5 th -Generation (5G) or 5G communication system to be provided for supporting higher data rates beyond 4 th -Generation (4G) communication system, such as long-term evolution (LTE), is disclosed. The system includes an apparatus of a base station. The apparatus may include: at least one transceiver, and at least one processor connected to the at least one transceiver, where the at least one processor is configured to transmit to a terminal, configuration information of reference signals for beam management regarding a transmit (Tx) beam of the BS or a receive (Rx) beam of the terminal, transmit the reference signals to the terminal, and the configuration information comprises information related to a number of repetitions of the reference signals.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation application of prior application Ser.No. 15/802,997, filed on Nov. 3, 2017, which was based on and claimedpriority under 35 U.S.C. § 119(a) of a Korean patent application number10-2016-0146677, filed on Nov. 4, 2016, in the Korean IntellectualProperty Office, the disclosure of which is incorporated by referenceherein in its entirety.

TECHNICAL FIELD

The present disclosure relates to wireless communication. Moreparticularly, the present disclosure relates to an apparatus and amethod for multiple-input multiple-output (MIMO) and beam management ina wireless communication system.

BACKGROUND

To meet the demand for wireless data traffic having increased sincedeployment of 4^(th) generation (4G) communication systems, efforts havebeen made to develop an improved 5^(th) generation (5G) or pre-5Gcommunication system. Therefore, the 5G or pre-5G communication systemis also called a ‘Beyond 4G Network’ or a ‘Post long-term evolution(LTE) System’.

The 5G communication system is considered to be implemented in higherfrequency millimeter wave (mmWave) bands, e.g., 60 GHz bands, so as toaccomplish higher data rates. To decrease propagation loss of the radiowaves and increase the transmission distance, the beamforming, massivemultiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO),array antenna, an analog beam forming, large scale antenna techniquesare discussed in 5G communication systems.

In addition, in 5G communication systems, development for system networkimprovement is under way based on advanced small cells, cloud radioaccess networks (RANs), ultra-dense networks, device-to-device (D2D)communication, wireless backhaul, moving network, cooperativecommunication, coordinated multi-points (CoMP), reception-endinterference cancellation and the like.

In the 5G system, Hybrid frequency shift key (FSK) and quadratureamplitude modulation (QAM) Modulation (FQAM) and sliding windowsuperposition coding (SWSC) as an advanced coding modulation (ACM), andfilter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA),and sparse code multiple access (SCMA) as an advanced access technologyhave been developed.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present disclosure.

SUMMARY

Aspects of the present disclosure are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentdisclosure is to provide an apparatus and a method for beam managementin a wireless communication system on the basis of the above-describeddiscussion.

In accordance with an aspect of the present disclosure, a method of abase station is provided. The method comprises performing a beamreference signal (BRS)-related signaling with a user equipment (UE), forbeam management. The method comprises transmitting to a terminal,configuration information of reference signals for beam managementregarding a transmit (Tx) beam of the BS or a receive (Rx) beam of theterminal and transmitting the reference signals to the terminal. Theconfiguration information may comprise information related to a numberof repetitions of the reference signals.

In accordance with another aspect of the present disclosure, a method ofa terminal is provided. The method comprises performing a BRS-relatedsignaling with a base station, for beam management. The method comprisesreceives, from a base station, configuration information of referencesignals for beam management regarding a transmit (Tx beam) of the BS ora receive (Rx) beam of the terminal and receives, from the base station,the reference signals. The configuration information comprisesinformation related to a number of repetitions of the reference signals.

In accordance with another aspect of the present disclosure, anapparatus of a base station is provided. The apparatus includes at leastone transceiver; and at least one processor connected to the at leastone transceiver, wherein the at least one processor is configured toperform a BRS-related signaling with a terminal, for beam management.The at least one transceiver is configured to transmit to a terminal,configuration information of reference signals for beam managementregarding a transmit (Tx) beam of the BS or a receive (Rx) beam of theterminal, and transmit the reference signals to the terminal. Theconfiguration information may comprise information related to a numberof repetitions of the reference signals.

In accordance with another aspect of the present disclosure, anapparatus of a terminal is provided. The apparatus includes at least onetransceiver; and at least one processor connected to the at least onetransceiver, wherein the at least one processor is configured to performa BRS-related signaling with a base station, for beam management. The atleast one processor is configured to receive, from a base station,configuration information of reference signals for beam managementregarding a transmit (Tx) beam of the BS or a receive (Rx) beam of theterminal, and receive, from the base station, the reference signals. Theconfiguration information comprises information related to a number ofrepetitions of the reference signals.

Various embodiments of the present disclosure enable operations for areference signal (RS) configuration for beam management, activation(and/or transmission) of pre-configured resources, and UE reporting onthe RS configuration therefor and the activation thereof.

Effects which can be obtained by the present disclosure are not limitedto the above-described effects, and other effects which have not beenmentioned may be clearly understood by those having ordinary knowledgein the technical field, to which the present disclosure pertains, fromthe following description.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 illustrates a wireless communication system according to variousembodiments of the present disclosure;

FIG. 2 illustrates the base station (BS) in the wireless communicationsystem according to various embodiments of the present disclosure;

FIG. 3 illustrates the terminal in the wireless communication systemaccording to various embodiments of the present disclosure;

FIG. 4 illustrates the communication interface in the wirelesscommunication system according to various embodiments of the presentdisclosure;

FIG. 5A illustrates examples of single-beam and multi-beam transmissiontransmission/reception points (TRPs) according to various embodiments ofthe present disclosure;

FIG. 5B illustrates a P-2 process based on two-level beam referencesignal (BRSs) and TRP triggering which is an example of scenario 1according to various embodiments of the present disclosure;

FIG. 5C illustrates an example of a network trigger in scenario 2according to various embodiments of the present disclosure;

FIG. 5D illustrates an example of a user equipment (UE) trigger inscenario 2 according to various embodiments of the present disclosure;

FIG. 5E illustrates an example of a network trigger in scenario 3according to various embodiments of the present disclosure;

FIG. 5F illustrates an example of a network trigger in scenario 4according to various embodiments of the present disclosure;

FIG. 5G illustrates an embodiment of two-level BRSs according to variousembodiments of the present disclosure;

FIG. 5H illustrates an example of a channel state information-referencesignal (CSI-RS) for P-2 according to various embodiments of the presentdisclosure;

FIG. 5I illustrates an example of a CSI-RS for P-3 according to variousembodiments of the present disclosure;

FIG. 5J illustrates another example of a CSI-RS for P-3 according tovarious embodiments of the present disclosure; and

FIG. 5K illustrates an example of an aperiodic RS for P-1 according tovarious embodiments of the present disclosure.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of variousembodiments of the present disclosure as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the various embodiments describedherein can be made without departing from the scope and spirit of thepresent disclosure. In addition, descriptions of well-known functionsand constructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of the presentdisclosure. Accordingly, it should be apparent to those skilled in theart that the following description of various embodiments of the presentdisclosure is provided for illustration purpose only and not for thepurpose of limiting the present disclosure as defined by the appendedclaims and their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Hereinafter, by way of example, various embodiments of the presentdisclosure will be described using a hardware-based approach. However,various embodiments of the present disclosure include technology usingboth hardware and software, and thus do not exclude a software-basedapproach.

Hereinafter, the present disclosure relates to an apparatus and a methodfor beam management in a wireless communication system. Specifically,the present disclosure will describe a signaling for operating a beamand technology for configuring a signaling in a wireless communicationsystem.

Signal-related terms (e.g., a reference signal (RS), a synchronizationsignal, and a beam RS), terms referring to configuration, termsreferring to network entities, terms referring to an element of anapparatus, and the like, which are used in the following description,are exemplified for convenience of description. Accordingly, the presentdisclosure is not limited to the following terms, and other terms havingequivalent technical meanings may be used.

Also, various embodiments of the present disclosure are described usingterms according to a certain communication standard (e.g., the ThirdGeneration Partnership Project (3GPP)), but this description is forillustrative purposes only. Various embodiments of the presentdisclosure may be easily modified and applied to another communicationsystem.

FIG. 1 illustrates a wireless communication system according to variousembodiments of the present disclosure.

Referring to FIG. 1, a base station (BS) 110, a terminal 120, and aterminal 130 are illustrated as the part of nodes using a wirelesschannel in a wireless communication system. FIG. 1 illustrates only oneBS, but another BS, which is the same as or similar to the BS 110, maybe further included.

The BS 110 is network infrastructure that provides wireless access tothe terminals 120 and 130. The BS 110 has coverage defined as apredetermined geographical region based on the distance at which asignal can be transmitted. The BS 110 may be referred to as “accesspoint (AP),” “eNodeB (eNB),” “5th generation (5G) node,” “wirelesspoint,” “transmission/reception point (TRP)” as well as “base station.”

Each of the terminals 120 and 130 is a device used by a user, andperforms communication with the BS 110 through a wireless channelDepending on the case, at least one of the terminals 120 and 130 mayoperate without user involvement. That is, at least one of the terminals120 and 130 is a device that performs machine-type communication (MTC)and may not be carried by the user. Each of the terminals 120 and 130may be referred to as “user equipment (UE),” “mobile station,”“subscriber station,” “remote terminal,” “wireless terminal,” or “userdevice” as well as “terminal.”

The BS 110, the terminal 120, and the terminal 130 may transmit andreceive wireless signals in millimeter wave (mmWave) bands (for example,28 GHz, 30 GHz, 38 GHz, and 60 GHz). At this time, in order to improve achannel gain, the BS 110, the terminal 120, and the terminal 130 mayperform beamforming. The beamforming may include transmissionbeamforming and reception beamforming That is, the BS 110, the terminal120, and the terminal 130 may assign directivity to a transmissionsignal and a reception signal. To this end, the BS 110 and the terminals120 and 130 may select serving beams 112, 113, 121, and 131 through abeam search procedure or a beam management procedure. After that,communications may be performed using resources having aquasi-co-located relationship with resources carrying the serving beams112, 113, 121, and 131.

A first antenna port and a second antenna ports are considered to bequasi co-located if the large-scale properties of the channel over whicha symbol on the first antenna port is conveyed can be inferred from thechannel over which a symbol on the second antenna port is conveyed. Thelarge-scale properties may include one or more of delay spread, dopplerspread, doppler shift, average gain, average delay, and spatial Rxparameters.

FIG. 2 illustrates the BS in the wireless communication system accordingto various embodiments of the present disclosure.

A structure exemplified at FIG. 2 may be understood as a structure ofthe BS 110. The term “-module”, “-unit” or “-er” used hereinafter mayrefer to the unit for processing at least one function or operation andmay be implemented in hardware, software, or a combination of hardwareand software.

Referring to FIG. 2, the BS may include a wireless communicationinterface 210, a backhaul communication interface 220, a storage unit230 (e.g., a memory), and a controller 240 (e.g., at least oneprocessor).

The wireless communication interface 210 performs functions fortransmitting and receiving signals through a wireless channel. Forexample, the wireless communication interface 210 may perform a functionof conversion between a baseband signal and bitstreams according to aphysical layer standard of the system. For example, in datatransmission, the wireless communication interface 210 generates complexsymbols by encoding and modulating transmission bitstreams. Further, indata reception, the wireless communication interface 210 reconstructsreception bitstreams by demodulating and decoding the baseband signal.

In addition, the wireless communication interface 210 up-converts thebaseband signal into a radio frequency (RF) band signal, transmits theconverted signal through an antenna, and then down-converts the RF bandsignal received through the antenna into the baseband signal. To thisend, the wireless communication interface 210 may include a transmissionfilter, a reception filter, an amplifier, a mixer, an oscillator, adigital-to-analog convertor (DAC), an analog-to-digital convertor (ADC),and the like. Further, the wireless communication interface 210 mayinclude a plurality of transmission/reception paths. In addition, thewireless communication interface 210 may include at least one antennaarray consisting of a plurality of antenna elements.

On the hardware side, the wireless communication interface 210 mayinclude a digital unit and an analog unit, and the analog unit mayinclude a plurality of sub-units according to operation power, operationfrequency, and the like. The digital unit may be implemented as at leastone processor (e.g., a digital signal processor (DSP)).

The wireless communication interface 210 transmits and receives thesignal as described above. Accordingly, the wireless communicationinterface 210 may be referred to as a “transmitter” a “receiver,” or a“transceiver.” Further, in the following description, transmission andreception performed through the wireless channel may be used to have ameaning including the processing performed by the wireless communicationinterface 210 as described above.

The backhaul communication interface 220 provides an interface forperforming communication with other nodes within the network. That is,the backhaul communication interface 220 converts bitstreams transmittedto another node, for example, another access node, another BS, a highernode, or a core network, from the BS into a physical signal and convertsthe physical signal received from the other node into the bitstreams.

The storage unit 230 stores a basic program, an application, and datasuch as setting information for the operation of the BS 110. The storageunit 230 may include a volatile memory, a non-volatile memory, or acombination of volatile memory and non-volatile memory. Further, thestorage unit 230 provides stored data in response to a request from thecontroller 240.

The controller 240 controls the general operation of the BS. Forexample, the controller 240 transmits and receives a signal through thewireless communication interface 210 or the backhaul communicationinterface 220. Further, the controller 240 records data in the storageunit 230 and reads the recorded data. The controller 240 may performsfunctions of a protocol stack that is required from a communicationstandard. According to another implementation, the protocol stack may beincluded in the wireless communication interface 210. According tovarious embodiments of the present disclosure, the controller 240 maycontrol the base station to perform operations (i.e. signalconfiguration, resource setting, report setting) according to thevarious embodiments of the present disclosure.

FIG. 3 illustrates the terminal in the wireless communication systemaccording to various embodiments of the present disclosure.

A structure exemplified at FIG. 3 may be understood as a structure ofthe terminal 120 or the terminal 130. The term “-module”, “-unit” or“-er” used hereinafter may refer to the unit for processing at least onefunction or operation, and may be implemented in hardware, software, ora combination of hardware and software.

Referring to FIG. 3, the terminal 120 includes a communication interface310, a storage unit 320 (e.g., a memory), and a controller 330 (e.g., atleast one processor).

The communication interface 310 performs functions fortransmitting/receiving a signal through a wireless channel. For example,the communication interface 310 performs a function of conversionbetween a baseband signal and bitstreams according to the physical layerstandard of the system. For example, in data transmission, thecommunication interface 310 generates complex symbols by encoding andmodulating transmission bitstreams. Also, in data reception, thecommunication interface 310 reconstructs reception bitstreams bydemodulating and decoding the baseband signal. In addition, thecommunication interface 310 up-converts the baseband signal into an RFband signal, transmits the converted signal through an antenna, and thendown-converts the RF band signal received through the antenna into thebaseband signal. For example, the communication interface 310 mayinclude a transmission filter, a reception filter, an amplifier, amixer, an oscillator, a DAC, and an ADC.

Further, the communication interface 310 may include a plurality oftransmission/reception paths. In addition, the communication interface310 may include at least one antenna array consisting of a plurality ofantenna elements. In the hardware side, the wireless communicationinterface 210 may include a digital circuit and an analog circuit (forexample, a radio frequency integrated circuit (RFIC)). The digitalcircuit and the analog circuit may be implemented as one package. Thedigital circuit may be implemented as at least one processor (e.g., aDSP). The communication interface 310 may include a plurality of RFchains. The communication interface 310 may perform beamforming.

The communication interface 310 transmits and receives the signal asdescribed above. Accordingly, the communication interface 310 may bereferred to as a “transmitter,” a “receiver,” or a “transceiver.”Further, in the following description, transmission and receptionperformed through the wireless channel is used to have a meaningincluding the processing performed by the communication interface 310 asdescribed above.

The storage unit 320 stores a basic program, an application, and datasuch as setting information for the operation of the terminal 120. Thestorage unit 320 may include a volatile memory, a non-volatile memory,or a combination of volatile memory and non-volatile memory. Further,the storage unit 320 provides stored data in response to a request fromthe controller 330.

The controller 330 controls the general operation of the terminal 120.For example, the controller 330 transmits and receives a signal throughthe communication interface 310. Further, the controller 330 recordsdata in the storage unit 320 and reads the recorded data. The controller330 may performs functions of a protocol stack that is required from acommunication standard. According to another implementation, theprotocol stack may be included in the communication interface 310. Tothis end, the controller 330 may include at least one processor ormicroprocessor, or may play the part of the processor. Further, the partof the communication interface 310 or the controller 330 may be referredto as a communication processor (CP). According to various embodimentsof the present disclosure, the controller 330 may control the terminalto perform operations (i.e. measurements of signals, reporting of themeasurement results) according to the various embodiments of the presentdisclosure.

FIG. 4 illustrates the communication interface in the wirelesscommunication system according to various embodiments of the presentdisclosure.

FIG. 4 shows an example for the detailed configuration of the wirelesscommunication interface 210 of FIG. 2 or the communication interface 310of FIG. 3. More specifically, FIG. 4 shows elements for performingbeamforming as part of the communication interface 210 of FIG. 2 or thecommunication interface 310 of FIG. 3.

Referring to FIG. 4, the communication interface 210 or 310 includes anencoding and circuitry 402, a digital circuitry 404, a plurality oftransmission paths 406-1 to 406-N, and an analog circuitry 408.

The encoding and circuitry 402 performs channel encoding. For thechannel encoding, at least one of a low-density parity check (LDPC)code, a convolution code, and a polar code may be used. The encoding andcircuitry 402 generates modulation symbols by performing constellationmapping.

The digital circuitry 404 performs beamforming for a digital signal (forexample, modulation symbols). To this end, the digital circuitry 404multiples the modulation symbols by beamforming weighted values. Thebeamforming weighted values may be used for changing the size and phraseof the signal, and may be referred to as a “precoding matrix” or a“precoder.” The digital circuitry 404 outputs the digitally beamformedmodulation symbols to the plurality of transmission paths 406-1 to406-N. At this time, according to a multiple input multiple output(MIMO) transmission scheme, the modulation symbols may be multiplexed,or the same modulation symbols may be provided to the plurality oftransmission paths 406-1 to 406-N.

The plurality of transmission paths 406-1 to 406-N convert the digitallybeamformed digital signals into analog signals. To this end, each of theplurality of transmission paths 406-1 to 406-N may include an inversefast fourier transform (IFFT) calculation unit, a cyclic prefix (CP)insertion unit, a DAC, and an up-conversion unit. The CP insertion unitis for an orthogonal frequency division multiplexing (OFDM) scheme, andmay be omitted when another physical layer scheme (for example, a filterbank multi-carrier (FBMC)) is applied. That is, the plurality oftransmission paths 406-1 to 406-N provide independent signal processingprocesses for a plurality of streams generated through the digitalbeamforming. However, depending on the implementation, some of theelements of the plurality of transmission paths 406-1 to 406-N may beused in common.

The analog circuitry 408 performs beamforming for analog signals. Tothis end, the digital circuitry 404 multiples the analog signals bybeamforming weighted values. The beamformed weighted values are used forchanging the size and phrase of the signal. More specifically, accordingto a connection structure between the plurality of transmission paths406-1 to 406-N and antennas, the analog circuitry 408 may be configuredin various ways. For example, each of the plurality of transmissionpaths 406-1 to 406-N may be connected to one antenna array. In anotherexample, the plurality of transmission paths 406-1 to 406-N may beconnected to one antenna array. In still another example, the pluralityof transmission paths 406-1 to 406-N may be adaptively connected to oneantenna array, or may be connected to two or more antenna arrays.

Various embodiments of the present disclosure relate generally towireless communication, and more particularly, to base station/UE (e.g.,TRP/UE) operations for P-1/P-2/P-3 which correspond to a beam managementprocedure among MIMO/beam management fields.

Various embodiments of the present disclosure relate to a P-1/P-2/P-3beam management process and a signaling (e.g., an RS) for the same in amulti-beam-based system. The present disclosure may include operationsfor RS configuration for beam management, activation (and/ortransmission) of pre-configured resources, and UE reporting on the RSconfiguration therefor and the activation thereof.

Prior to a detailed description of the present disclosure, hereinafter,the meanings of the terms used in the disclosure will be described.1)-3) will be described with reference to full dimension (FD)-MIMO studyitem (SI) (TR36.897).

1) Hybrid-beamforming (BF): an architecture for dynamically changing atransceiver unit (TXRU) virtualization weight (i.e., the phase andamplitude of analog BF) over time.

2) Digital-BF: refers to the case of execution of a static TXRUvirtualization weight(s). However, digital-BF may represent a form of achange in a digitally-formed beam over time.

3) Single-beam approach: signifies a case where a beam generated by abase station is sufficiently wide and a service area is covered withouta sweeping operation.

4) Multi-beam: signifies a case where a beam generated by a base stationis narrow and a service area is covered with the need to involve asweeping operation.

5) Beam sweeping: signifies an action which in order to prevent theoccurrence of an angular coverage hole at the time of generation of abeam, adjusts the beam in all directions of a cell during apredetermined time period and transmits a signal (refer to FIG. 1).

FIG. 5A illustrates examples of single-beam and multi-beam transmissionTRPs according to various embodiments of the present disclosure.

6) Non-Zero Power channel state information-reference signal CSI-RS (NZPCSI-RS): signifies an RS used for beam measurement in the presentdisclosure. An RS may be a UE-specific RS. “NZP” is used to distinguishan NZP CSI-RS from a Zero Power CSI-RS (ZP CSI-RS).

7) ZP CSI-RS: is a resource that when a relevant resource (e.g., afrequency/time resource) includes an NZP CSI-RS allocated to a differentUE in reception of data by a UE, a base station (e.g., a TRP) notifiesthe UE of in order to help the UE to be capable of excluding therelevant resource and decoding the data.

8) Beam management procedure P-1: signifies a process for associating atransmission beam of a base station (e.g., a TRP Tx beam) with areception beam of a UE (e.g., a UE Rx beam).

9) Beam management procedure P-2: signifies a process for refining atransmission beam of a base station (e.g., a TRP Tx beam).

10) Beam management procedure P-3: signifies a process for refining areception beam of a UE (e.g., a UE Rx beam).

11) Next generation Node B (gNB): may include a single TRP or multipleTRPs. Hereinafter, the term “base station” used in the presentdisclosure may refer to a single gNB, a single TRP, or a single TRPcluster (i.e., a cluster including multiple TRPs). One gNB may exist ina cell. When each of multiple TRPs or a TRP cluster within each celloperates as a single beam, the cell may be recognized as a single-beamtransmission cell. That is, for example, when a single TRP exists in onecell, this case may be expressed as TRP=TRP cluster=gNB=cell.

12) UE: refers to a user equipment.

The present disclosure proposes a utilization scenario of varioussignalings for the above-described P-1/P-2/P-3 beam management andproposes operations of base station/UE according to the utilizationscenario. For beam management, the scenarios shown in Table 1 below maybe implemented.

TABLE 1 (Various beam management RS scenarios) P-1 P-2 P-3 Scenario 1cell-specific signal (sync signal, new RS, . . .) Scenario 2cell-specific signal UE-specific RS (new RS, sync signal) Scenario 3UE-specific RS Scenario 4 sync signal (i.e., UE-specific RS compositebeam) + UE-specific RS (- use of smaller amount of resources than thatof RS for P-1 of scenario 2 - execution of fine beam association throughUE-specific RS)

In Table 1, cell-specific RS configuration may be performed based on

Alt 1. System information,

Alt 2. Message (Msg) 4 of a random-access channel (RACH) process, and

Alt 3. physical downlink shared channel (PDSCH) transmitted after aRACH. In Table 1, a UE-specific RS may be configured through aUE-specific radio resource control (RRC) signaling. Through the RS, a UEmay measure the quality, for example, the strength of a signal (i.e.,reference signal received power (RSRP)) of a beam for beam management.The UE may transmit IDs and/or corresponding RSRPs of one or morepreferred beams, as reporting on the measurement. Hereinafter, the term“UE reporting” may refer to an operation of a UE for feeding back a beamID and/or RSRP.

According to various embodiments of the present disclosure, aUE-specific RS may be variously configured. For example, the UE-specificRS may be a periodic, semi-static, or aperiodic CSI-RS. An aperiodicUE-specific RS may be configured through an RRC signaling, and may thenactivate the transmission of a CSI-RS through downlink controlinformation (DCI)/medium access control (MAC)-control element (CE) andthe like. A semi-static CSI-RS refers to a type in which the semi-staticCSI-RS is periodically transmitted when a configured CSI-RS becomes “on”in DCI/MAC-CE, and is not transmitted when the configured CSI-RS becomes“off” in DCI/MAC-CE.

Hereinafter, for convenience of description, the cell-specific RS andUE-specific RS for beam management shown in Table 1 will be referred toas “beam RS (BRS)” and “CSI-RS”, respectively.

Hereinafter, operations of base station/UE for each scenario will bedefined. However, the operations described below are described asexamples according to various embodiments of the present disclosure, andthus, embodiments of the present disclosure are not limited to theoperations of base station/UE described below.

[Scenario 1]

Step 1) Configuration of a BRS

Alt 1. Configuration and utilization of a single BRS for P-1/P-2/P-3,and

Alt 2. Configuration and utilization of a BRS for P-1 (i.e., BRS1) and aBRS for P-2 (i.e., BRS2);

Step 2) P-2 triggering by a TRP or UE when necessary;

Alt 1. Network triggering: sends a request for reporting on informationon P-2 through DCI or MAC-CE to the UE, and

Alt 2. UE triggering: the UE reports relevant information whenrecognizing the need of the relevant information; and

Step 3) UE reporting for P-2.

FIG. 5B illustrates a P-2 process based on two-level BRSs and TRPtriggering which is an example of scenario 1 according to variousembodiments of the present disclosure. FIG. 5B illustrates operations ofTRP-UE in the case of Step 1)-Alt 2 and P-2 triggering by a TRP inrelation to scenario 1.

In scenario 1, P-3 may be solved by a UE implementation issue.

[Scenario 2]

Step 1) Configuration of a BRS to be used when P-1 operates;

Step 2) UE reporting for P-1;

Step 3) Configuration of an NZP CSI-RS and a ZP CSI-RS through an RRCsignaling, for P-2/P-3;

Step 4) P-2 or P-3 triggering by a TRP or UE when necessary

:particularly, when a semi-persistent CSI-RS and an aperiodic CSI-RS areconfigured,

Alt 1. Network triggering: a base station may specify a CSI-RS resourcethrough DCI or MAC-CE. The base station may request a UE to reportinformation on P-2 or P-3.

FIG. 5C illustrates an example of a network trigger in scenario 2according to various embodiments of the present disclosure.

Alt 2. UE triggering: according to the need, the UE may requesttransmission of a CSI-RS. Then, the base station operates in a schemeidentical/similar to that of Alt 1.

FIG. 5D illustrates an example of a UE trigger in scenario 2 accordingto various embodiments of the present disclosure.

Step 5) UE reporting for P-2 or P-3.

Operations of the TRP-UE according to scenario 2 are illustrated inFIGS. 5C and 5D.

[Scenario 3]

Step 1) Configuration of an NZP CSI-RS and a ZP CSI-RS for operation ofP-1/P-2/P-3 through an RRC signaling;

Step 2) UE reporting for P-1;

Step 3) P-2 or P-3 triggering by a TRP or UE when necessary

:particularly, when a semi-persistent CSI-RS and an aperiodic CSI-RS areconfigured,

Alt 1. Network triggering: the network (i.e. base station, gNB) assignsa CSI-RS resource through DCI or MAC-CE and requests the UE to reportinformation on P-2 or P-3, and

Alt 2. UE triggering: the UE requests transmission of a relevant CSI-RSwhen recognizing the need of the relevant CSI-RS. A subsequent operationof the base station is identical to that of Alt 1; and

Step 4) UE reporting for P-2 or P-3.

Operations of the TRP-UE according to scenario 3 are illustrated in FIG.5E.

FIG. 5E illustrates an example of a network trigger in scenario 3according to various embodiments of the present disclosure.

[Scenario 4]

Step 1) UE composite beam selection and reporting;

Step 2) Configuration of an NZP CSI-RS and/or a ZP CSI-RS for operationof P-1/P-2/P-3 through an RRC signaling

:according to various embodiments of the present disclosure, an NZPCSI-RS for P-1 may be dependent on the number of composite beams. Thatis, when BRS1 of scenario 1 is compared with a CSI-RS of scenario 3, itmay be possible to operate a CSI-RS for P-1 with a relatively leandesign;

Step 3) UE reporting on P-1;

Step 4) P-2 or P-3 triggering by a TRP or UE when necessary

:particularly, when a semi-persistent CSI-RS and an aperiodic CSI-RS areconfigured,

Alt 1. Network triggering: the network (i.e. base station, gNB)specifies a CSI-RS resource through DCI or MAC-CE and requests the UE toreport information on P-2 or P-3, and

Alt 2. UE triggering: the UE requests transmission of a relevant CSI-RSwhen recognizing the need of the relevant CSI-RS. A subsequent operationof the base station is identical to that of Alt 1;

Step 5) UE reporting for P-2 or P-3;

Step 6) When an index of a preferred composite beam of the UE ischanged, the UE reports, to the base station, the changed indexinformation of the preferred composite beam;

Step 7) The base station applies the changed beam to a relevant CSI-RSresource for P-1; and

Step 8) UE reporting by the UE for execution of P-1.

Operations of the TRP-UE according to scenario 4 are illustrated in FIG.5F.

FIG. 5F illustrates an example of a network trigger in scenario 4according to various embodiments of the present disclosure.

In scenario 4, a composite beam may signify a wide beam formed bycombining multiple narrow beams used in downlink before a UE associatesa transmission beam of a base station (e.g., a TRP Tx beam) with areception beam of the UE (e.g., a UE Rx beam). According to variousembodiments of the present disclosure, a composite beam may be utilizedto transmit a synchronization and physical broadcast channel (PBCH) andthe like.

Next, various and detailed embodiments of the present disclosure in oneor more scenarios will be described.

[Two-Level BRSs: Applicable to Scenario 1]

When a cell-specific RS BRS1 is used for P-1 and P-3 and BRS2 is usedfor P-2 and P-3, BRS1 and BRS2 may be configured through identical ordifferent physical channels. For example, BRS1 may be configured througha master information block (MIB), and then, whether BRS2 is configuredthrough a system information block (SIB) or whether BRS2 is used in aSIB may be configured. Basically, only BRS1 may be used for measurementfor handover. BRS2 configuration information may include the followingparameters, and an embodiment of the BRS2 configuration information isillustrated in FIG. 5G.

FIG. 5G illustrates an embodiment of two-level BRSs according to variousembodiments of the present disclosure.

1. #of refinement symbols (#of orthogonal frequency divisionmultiplexing (OFDM) symbols in BRS2), and

2. Periodicity.

[Configurable Cell-Specific RS: Applicable to Scenario ½]

According to various embodiments of the present disclosure, a system maydetermine that a periodicity of a cell-specific RS defined to performP-1 is flexible. For example, when the number of UEs which are in aconnected state in a cell is not large, a periodicity of a relevant RSmay be kept long. A periodicity of the relevant RS may be configuredthrough sync and system information. When a periodicity of the relevantRS is configured through sync, it is possible to distinguish periodicityconfigurations through a sequence of a primary synchronization signal(PSS), a secondary synchronization signal (SSS), or an extendedsynchronization signal (ESS).

[Configuration of UE-Specific RS for UE Capability-Based BeamManagement: Applicable to Scenario 2/3/4]

According to various embodiments of the present disclosure, a UE mayrequest a base station to configure an RS. That is, an RS for P-3 may beconfigured based on the request of the UE. The UE may transmitinformation related to the number of beams to a base station. Forexample, for refinement of a reception beam, the UE may notify a TRP ofinformation related to the number of Rx beams for training. Theinformation may be utilized to determine, for P-3, the number ofrepetitive transmissions of an RS to the UE in relation to a given TRPTx beam. In other words, the information may include information for thenumber of repetitive transmissions of an RS (e.g., a CSI-RS). Theinformation may be transmitted through a higher layer signaling, MAC-CE,or UCI. The number of Rx beams desired for training, which is requestedby the UE, may be determined based on at least one of the number oftransceiver units (TXRUs) possessed by the UE, whether multi-beamsweeping is to be performed, and the number of beams. In order for theUE to transmit the relevant information to the TRP, the followingvarious schemes may be used.

Alt 1a. [applicable to all TRP/UE triggering situations] Scheme fortransmitting the relevant information through message 3 (Msg3) during arandom-access process.

Alt 2a. [applicable to all TRP/UE triggering situations] Scheme fortransmitting the relevant information through a UE capabilitynegotiation process (e.g., UE capability information) after connectionestablishment, and

Alt 3a. [applicable to only UE triggering situation] Scheme fortransmitting the relevant information together with P-3 duringtransmission of a trigger request message.

A base station may determine the number of repetitions of an RS (e.g., aCSI-RS) on the basis of a request of a UE. For example, the base stationmay determine the number of repetitions of a CSI-RS on the basis ofinformation (e.g., capability information) received from the UE, and mayallocate resources by the number of repetitions. Information on arequest for the number of repetitions of an RS in relation to a givenTRP TX beam, which has been requested by the UE, may be determined bythe base station (a base station that controls a TRP). The base station(a base station that controls a TRP) may accept a value, which has beenrequested by the UE, without any change according to a resourceavailability situation, and may determine the number of repetitions ofthe RS. Alternatively, the base station does not accept the value, butmay determine the number of repetitions of the RS according to adifferent scheme. The UE may be notified of the number of repetitions ofthe RS in relation to the given TRP TX beam for P-3, which has beendetermined by the base station, according to the following schemes (forexample, information for indicating the repetitions of the RS can bereferred as the repetition information).

Alt 1b. [when UE request information is received through Alt 1a and Alt2a] Method for including the repetition information during configurationof an NZP/ZP CSI-RS in an RRC (reconfiguration) signaling, and

Alt 2b. [when UE request information is received through Alt 1a, Alt 2a,and Alt 3a] Method, when transmission of an NZP/ZP CSI-RS configuredthrough an RRC (reconfiguration) signaling is activated throughDCI/MAC-CE, for including together, the repetition information in it(DCI/MAC-CE).

[NZP/ZP UE-Specific RS for Beam Management: In Relation to Scenario2/3/4]

According to various embodiments of the present disclosure, theconfiguration of an NZP CSI-RS for P-2 may include the followingparameters.

1. #of antenna ports=#of TRP Tx beams in a single time instance,

2. #of OFDM symbols for refinement,

3. Resource configuration: a pattern (e.g., a start OFDM symbol numberwithin a subframe (SF), and a start subcarrier index within a resourceblock (RB)), a CSI-RS transmission frequency resource (a sub-band orwide-band), and a start SF number within a frame, and

4. Periodicity: defined only in the case of a periodic CSI-RS.

According to various embodiments of the present disclosure, theconfiguration of an NZP CSI-RS for P-3 may include the followingparameters.

1. #of repetitions of a CSI-RS: may be selected based on information ona request for the number of repetitions of an RS related to a given TRPTx beam which is requested by a UE.

2. Resource configuration: a pattern (e.g., a start OFDM symbol numberwithin an SF, and a start subcarrier index within an RB), a CSI-RStransmission frequency resource (a sub-band or wide-band), and a startSF number within a frame, and

3. Periodicity: defined only in the case of a periodic CSI-RS.

In some embodiments of the present disclosure, when information on thenumber of repetitions of an RS related to a given TRP Tx beam for P-3 istransmitted through DCI or MAC-CE, information on #(number) ofrepetitions of a CSI-RS may be excluded from the configuration of an NZPCSI-RS for P-3.

In some embodiments of the present disclosure, when configurations forP-2 and P-3 are independently configured, parameters within eachconfiguration may be configured as described above. However, in someother embodiments of the present disclosure, when P-2 and P-3 areconfigured in an identical format, the parameters for the configurationmay be as described below.

1. #of antenna ports=#of TRP Tx beams in a single time instance,

2. #of OFDM symbols for TRP Tx beam refinement,

3. #of repetitions of a CSI-RS: selected based on information on arequest for the number of repetitions of an RS related to a given TRP Txbeam which is requested by a UE.

4. Resource configuration: a pattern (e.g., a start OFDM symbol numberwithin an SF, and a start subcarrier index within an RB), a CSI-RStransmission frequency resource (a sub-band or wide-band), and a startSF number within a frame, and

5. Periodicity: defined only in the case of a periodic CSI-RS.

When P-2 and P-3 are configured in an identical format, multiple CSI-RSconfigurations (an ID may be assigned to each configuration) may beincluded in one CSI process within an RRC message. Thereafter,transmitting of a CSI-RS by using a corresponding configuration IDthrough DCI/MAC-CE may be activated. Hereinafter, FIGS. 5H, 5I, and 5Jillustrate examples of CSI-RSs transmitted for P-2 and P-3. FIGS. 5H to5J illustrate mapping on a one RB-by-one RB basis. In some embodimentsof the present disclosure, this mapping may be repeated in all RBs in asystem bandwidth (BW).

FIG. 5H illustrates an example of a CSI-RS for P-2 according to variousembodiments of the present disclosure.

Referring to FIG. 5H, FIG. 5H illustrates an embodiment in which theparameters for configuration of a CSI-RS for P-2 are as follows:

1. #of antenna ports=4,

2. #of OFDM symbols for refinement=1, and

3. Start OFDM symbol number within an SF=0 and a start subcarrier indexwithin an RB=2.

FIG. 5I illustrates an example of a CSI-RS for P-3 according to variousembodiments of the present disclosure.

Referring to FIG. 5I, FIG. 5I illustrates an embodiment in which theparameters for configuration of a CSI-RS for P-3 are as follows:

1. #of repetitions of a CSI-RS=4, and

2. Start OFDM symbol number within an SF=0 and a start subcarrier indexwithin an RB=2.

In the embodiment illustrated in FIG. 5I, repetitive RSs are transmittedthrough consecutive symbols, but embodiments of the present disclosureare not limited thereto. In another embodiment of the presentdisclosure, RSs may be transmitted through non-consecutive symbols.

FIG. 5J illustrates another example of a CSI-RS for P-3 according tovarious embodiments of the present disclosure.

Referring to FIG. 5J, FIG. 5J illustrates an embodiment in which a widersubcarrier spacing is used for a CSI-RS for P-3, and parameters, some ofwhich are different from those of the above-described configuration ofan NZP CSI-RS for P-3, may be utilized. For example, the parameters areas follows:

1. #of repetitions of a CSI-RS in an OFDM symbol,

2. #of OFDM symbols for repetition,

3. Resource configuration: a pattern (e.g., a start OFDM symbol withinan SF, and a start subcarrier index within an RB), a CSI-RS transmissionfrequency resource (a sub-band or wide-band), and a start SF numberwithin a frame, and

4. Periodicity: defined only in the case of a periodic CSI-RS.

By increasing a subcarrier spacing of a CSI-RS, multiple CSI-RSs may betransmitted during one OFDM symbol duration. A CSI-RS may use asubcarrier spacing of the CSI-RS which is lengthened according to the#of repetitions representing the number of repetitions of the CSI-RS.Alternatively, after a subcarrier spacing of a CSI-RS for P-3 ispredesignated (e.g., 4 to 10 subcarriers), as many as correspondingsub-symbols may be used to transmit the CSI-RS. For example, when asubcarrier spacing of a CSI-RS for P-3 is limited to a distance equal tofour times a subcarrier spacing for data:

i) When an RS is desired to be repeated four times, one OFDM symbol (oneOFDM symbol includes four sub-symbols) is used to transmit a CSI-RS.

ii) When an RS is desired to be repeated eight times, two OFDM symbolsare used to transmit a CSI-RS.

The configuration of a ZP CSI-RS for P-2 and P-3 may include thefollowing parameters.

1. #of antenna ports=#of beams in a single time instance,

2. #of OFDM symbols: related to #of OFDM symbols for TRP Tx beamrefinement and #of a repeated RS,

3. #of repetitions of a CSI-RS in an OFDM symbol (used only when asubcarrier spacing for a CSI-RS is adjusted),

4. Resource configuration: a pattern (e.g., a start OFDM symbol numberwithin an SF, and a start subcarrier index within an RB), a CSI-RStransmission frequency resource (a sub-band or wide-band), and a startSF number within a frame, and

5. Periodicity: defined only in the case of configuration of a ZP CSI-RSfor a periodic CSI-RS.

[Utilization Scenario of Two Types of P-1's ((1) P-1 for Typical(Periodic) TRP Tx/UE Rx Beam Association, and (2) P-1 for a Situationwhere a TRP Tx/UE Rx Beam Needs to be Suddenly Changed) and RelatedProcedures: Applicable to Scenario 1/2/3/4]

As an RS for supporting P-1, a periodic or aperiodic type of RS may beconfigured. A periodic RS may be transmitted for initial TRP Tx-UE Rxbeam association and subsequent update, and refers to theabove-introduced RS for P-1. An aperiodic RS may be transmitted for thepurpose that beams currently associated with each other are determinedto be inappropriate and a TRP Tx-UE Rx beam is desired to be suddenlychanged. According to various embodiments of the present disclosure, anaperiodic RS may be initiated by a base station of an aperiodic RS(network-based triggering) or be initiated by a request of a UE(UE-based triggering).

As an RS pattern capable of being predesignated between a TRP and a UEof an aperiodic RS for supporting P-1, the following Alts exist.

Alt 1. A base station may repetitively transmit an RS designated for P-1by the value determined based on the above-described UE beam sweepingcapability. At this time, according to various embodiments of thepresent disclosure, RSs designated for P-1 may be mapped to consecutivesymbols or SFs.

Alt 2. A base station may use RSs configured for P-2 and P-3.

When transmission of an RS (i.e. aperiodic RS for P-1) is activatedthrough DCI/MAC-CE in relation to Alt 2, P-2/P-3 may operate in the formof simultaneously activating the transmission of an RS.

FIG. 5K illustrates an example of an aperiodic RS for P-1 according tovarious embodiments of the present disclosure.

FIG. 5K illustrates operations of TRP-UE related to an aperiodic RS forP-1 according to a request of a UE in scenario 2.

Methods according to claims of the present disclosure or embodimentsdescribed in the specification of the present disclosure may beimplemented in the form of hardware, software, or a combination ofhardware and software.

When the methods are implemented in software, a computer-readablestorage medium that stores one or more programs (software modules) maybe provided. The one or more programs stored in the computer-readablestorage medium may be configured for execution by one or more processorswithin an electronic device. The one or more programs may includeinstructions which cause the electronic device to perform the methodsaccording to the claims of the present disclosure or the embodimentsdescribed in the specification of the present disclosure.

The programs (software modules or software) may be stored in randomaccess memories, non-volatile memories including flash memories,read-only memories (ROMs), electrically erasable programmable ROM(EEPROMs), magnetic disc storage devices, compact disc-ROMs (CD-ROMs),digital versatile discs (DVDs), other types of optical storage devices,or magnetic cassettes. Alternatively, the programs may be stored in amemory configured by a combination of some or all of such storagedevices. Also, each of the memories may be provided in plurality.

Further, the programs may be stored in an attachable storage device thatcan be accessed by the electronic device through a communication networksuch as the Internet, Intranet, local area network (LAN), wireless LAN(WLAN), or storage area network (SAN), or through a communicationnetwork configured by a combination thereof. This storage device may beconnected through an external port to the electronic device performingembodiments of the present disclosure. Alternatively, a separate storagedevice on a communication network may be connected to the electronicdevice performing embodiments of the present disclosure.

In the above-described specific embodiments of the present disclosure,the elements included in the present disclosure are expressed in asingular form or a plural form according to the proposed specificembodiment. However, the singular or plural expression is selectedappropriately for the situation proposed for convenience of description,the present disclosure is not limited to a single element or multipleelements, and the elements expressed in a plural form may be configuredas a single element or an element expressed in a singular form may beconfigured as multiple elements.

While the present disclosure has been shown and described with referenceto various embodiments thereof, it will be understood by those skilledin the art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the present disclosure asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A method performed by a user equipment (UE), themethod comprising: receiving, from a base station, a radio resourcecontrol (RRC) message including at least one of: first information onone or more first channel state information-reference signal (CSI-RS)configurations associated with a semi-persistent CSI-RS, or secondinformation on one or more second CSI-RS configurations associated withan aperiodic CSI-RS; in case that a medium access control (MAC) controlelement (CE) for activating a first CSI-RS configuration from the one ormore first CSI-RS configurations is received, receiving, from the basestation, at least one CSI-RS using a periodicity based on the firstCSI-RS configuration; and in case that downlink control information(DCI) for indicating a second CSI-RS configuration from the one or moresecond CSI-RS configurations is received, receiving, from the basestation, an aperiodic CSI-RS based on the second CSI-RS configuration.2. The method of claim 1, wherein the MAC CE includes an identifier ofthe CSI-RS configuration, and wherein the CSI-RS configuration includesinformation on the periodicity for the at least one CSI-RS.
 3. Themethod of claim 1, wherein the CSI-RS configuration includes resourceinformation on a CSI-RS resource, and wherein the resource informationincludes: a number of antenna ports for the CSI-RS resource, a startorthogonal frequency division multiplexing (OFDM) symbol number within aresource block used for CSI-RS transmission, and frequency resources forthe CSI-RS resource.
 4. The method of claim 1, further comprising:receiving, from the base station, a MAC CE for deactivating the CSI-RSconfiguration, wherein the at least one CSI-RS is received according tothe periodicity between the activation of the first CSI-RS configurationand the deactivation of the first CSI-RS configuration.
 5. The method ofclaim 1, further comprising: receiving, from the base station,information for configuring the UE to report a beam identifier (ID) anda reference signal received power (RSRP), wherein the CSI-RSconfiguration includes repetition information for indicating thatCSI-RSs are transmitted with a same transmit beam of the base stationand are transmitted on different orthogonal frequency divisionmultiplexing (OFDM) symbols.
 6. A method performed by a base station(BS), the method comprising: transmitting, to a user equipment (UE), aradio resource control (RRC) message including at least one of: firstinformation on one or more first channel state information-referencesignal (CSI-RS) configurations associated with a semi-persistent CSI-RS,or second information on one or more second CSI-RS configurationsassociated with an aperiodic CSI-RS; in case that a medium accesscontrol (MAC) control element (CE) for activating a first CSI-RSconfiguration from the one or more CSI-RS configurations is transmitted,transmitting, to the UE, at least one CSI-RS using a periodicity basedon the first CSI-RS configuration; and in case that downlink controlinformation (DCI) for indicating a second CSI-RS configuration from theone or more second CSI-RS configurations is transmitted, transmitting,to the UE, an aperiodic CSI-RS based on the second CSI-RS configuration.7. The method of claim 6, wherein the MAC CE includes an identifier ofthe CSI-RS configuration, and wherein the CSI-RS configuration includesinformation on the periodicity for the at least one CSI-RS.
 8. Themethod of claim 6, wherein the CSI-RS configuration includes resourceinformation on a CSI-RS resource, and wherein the resource informationincludes: a number of antenna ports for the CSI-RS resource, a startorthogonal frequency division multiplexing (OFDM) symbol number within aresource block used for CSI-RS transmission, and frequency resources forthe CSI-RS resource.
 9. The method of claim 6, further comprising:transmitting, to the UE, a MAC CE for deactivating the CSI-RSconfiguration, wherein the at least one CSI-RS is transmitted accordingto the periodicity between the activation of the first CSI-RSconfiguration and the deactivation of the first CSI-RS configuration.10. The method of claim 6, further comprising: transmitting, to the UE,information for configuring the UE to report a beam identifier (ID) anda reference signal received power (RSRP), wherein the CSI-RSconfiguration includes repetition information for indicating thatCSI-RSs are transmitted with a same transmit beam of the base stationand are transmitted on different orthogonal frequency divisionmultiplexing (OFDM) symbols.
 11. A user equipment (UE) comprising: atleast one transceiver; and at least one processor configured to:receive, from a base station via the at least one transceiver, a radioresource control (RRC) message including at least one of: firstinformation on one or more first channel state information-referencesignal (CSI-RS) configurations associated with a semi-persistent CSI-RS,or second information on one or more second CSI-RS configurationsassociated with an aperiodic CSI-RS, in case that a medium accesscontrol (MAC) control element (CE) for activating a first CSI-RSconfiguration from the one or more first CSI-RS configurations isreceived, receive, from the base station via the at least onetransceiver, at least one CSI-RS using a periodicity based on the firstCSI-RS configuration, and in case that downlink control information(DCI) for indicating a second CSI-RS configuration from the one or moresecond CSI-RS configurations is received, receive, from the base stationvia the at least one transceiver, an aperiodic CSI-RS based on thesecond CSI-RS configuration.
 12. The UE of claim 11, wherein the MAC CEincludes an identifier of the CSI-RS configuration, and wherein theCSI-RS configuration includes information on the periodicity for the atleast one CSI-RS.
 13. The UE of claim 11, wherein the CSI-RSconfiguration includes resource information on a CSI-RS resource, andwherein the resource information includes: a number of antenna ports forthe CSI-RS resource, a start orthogonal frequency division multiplexing(OFDM) symbol number within a resource block used for CSI-RStransmission, and frequency resources for the CSI-RS resource.
 14. TheUE of claim 11, wherein the at least one processor is further configuredto receive, from the base station via the at least one transceiver, aMAC CE for deactivating the CSI-RS configuration, and wherein the atleast one CSI-RS is received according to the periodicity between theactivation of the first CSI-RS configuration and the deactivation of thefirst CSI-RS configuration.
 15. The UE of claim 11, wherein the at leastone processor is further configured to receive, from the base stationvia the at least one transceiver, information for configuring the UE toreport a beam identifier (ID) and a reference signal received power(RSRP), and wherein the CSI-RS configuration includes repetitioninformation for indicating that CSI-RSs are transmitted with a sametransmit beam of the base station and are transmitted on differentorthogonal frequency division multiplexing (OFDM) symbols.
 16. A basestation comprising: at least one transceiver; and at least one processorconfigured to: transmit, to a user equipment (UE) via the at least onetransceiver, a radio resource control (RRC) message including at leastone of: first information on one or more first channel stateinformation-reference signal (CSI-RS) configurations associated with asemi-persistent CSI-RS, or second information on one or more secondCSI-RS configurations associated with an aperiodic CSI-RS, in case thata medium access control (MAC) control element (CE) for activating afirst CSI-RS configuration from the one or more first CSI-RSconfigurations is transmitted, transmit, to the UE via the at least onetransceiver, at least one CSI-RS using a periodicity based on the firstCSI-RS configuration, and in case that downlink control information(DCI) for indicating a second CSI-RS configuration from the one or moresecond CSI-RS configurations is transmitted, transmit, to the UE, anaperiodic CSI-RS based on the second CSI-RS configuration.
 17. The basestation of claim 16, wherein the MAC CE includes an identifier of theCSI-RS configuration, and wherein the CSI-RS configuration includesinformation on the periodicity for the at least one CSI-RS.
 18. The basestation of claim 16, wherein the CSI-RS configuration includes resourceinformation on a CSI-RS resource, and wherein the resource informationincludes: a number of antenna ports for the CSI-RS resource, a startorthogonal frequency division multiplexing (OFDM) symbol number within aresource block used for CSI-RS transmission, and frequency resources forthe CSI-RS resource.
 19. The base station of claim 16, wherein the atleast one processor is further configured to transmit, to the UE via theat least one transceiver, a MAC CE for deactivating the CSI-RSconfiguration, and wherein the at least one CSI-RS is received accordingto the periodicity between the activation of the first CSI-RSconfiguration and the deactivation of the first CSI-RS configuration.20. The base station of claim 16, wherein the at least one processor isfurther configured to transmit, to the UE via the at least onetransceiver, information for configuring the UE to report a beamidentifier (ID) and a reference signal received power (RSRP), andwherein the CSI-RS configuration includes repetition information forindicating that CSI-RSs are transmitted with a same transmit beam of thebase station and are transmitted on different orthogonal frequencydivision multiplexing (OFDM) symbols.